Aircraft covering



ISADORE m. assessor-11v, or cmoaeo, rumors, AND STARR TRUSCOTT, or Ermine-- HAM, omo.

AIRCRAFT C( JVERING.

No Drawing.

This invention relates to improvements in flexible gas retaining fabrics for aircraft and more particularly "to the gas retaining fabric used in the gas cells of aircraft of the Zeppelin type. l

One of the objects of the present invention is to provide an impermeable flexible membrane or covering of the above general character which may be inexpensively manufactured and fabricated into gas retaining bags or cells. 7

A further object is to provide a fabric of the above .general character adapted to eliminate the use of goldbeaters skins heretofore considered essential.

Other objects will be in part obvious and in part hereinafter pointed out.

It is our belief that cellulose, except in the form of its esters and ethers, has not previously been dispersed in any of the solvents capable of dispersing rubber. From theresults of experiments we are convinced that films prepared from such dispersions of cellulose and rubber. have Very high resistance to the passage of gases. These films may be applied to a base cloth or fabric or produced independently and applied to cloth or fabric by means of cement. There are doubtless other uses to which this material may be put.

In order to obtain cellulose in the form in which it may be dispersed in organic solvents viscose, or other aqueous dispersion of cellulose derivative. and latex arethoroughly mixed. If desired, accelerators, activators, antioxidants, and other materials which have been found to give desirable properties to rubber compounds may be incorporated in the mixture. They maybe added in the beginning, or may be milled into the coagulated mixture at a later stage oughly wit or may be added to the dispersion of the mixture in the organic solvent. When the entire mixture has become hom- 'ogeneous the mixture is poured, or forcedthrough an orifice, or passed in any other manner into a bath capable of coagulating the viscose-latex mixture. The product is allowed to remain in this bath until completely coa ulated. It is then washed thorwater in order to remove all Water soluble material contained in it. This product is then drained and dried prefer- .ablyll y-. passing a-current of air over or' through it, atnorm'al temperatures. When Application filed April 11, 1925.

Serial No. 22,348.

dried itis milled a sufiicient length of time so that it may readily be dispersed in the medium desired. The following examples will illustrate the method. 1

Two thousand gms. of. viscose, prepared from 150 gms. of cellulose, namely, cotton linters, is mixed thoroughly with 375 gms. of rubber latex, containing 40% of nonvolatile material. The mixture obtained is. poured into a bath containing a 10% solution of acetic acid, in a fine stream such that a heavy thread-is formed upon coagulation. The thickness of this thread should be not over 2 to 3 mm. in order to facilitate washing and drying. The coagulated mass is allowed to remain in the coagulating bath for a period of three hours. After this time it is drained and washed thoroughly in running cold water until the washings no longer show an acid reaction. The product is then drained and air dried, whereupon its color changes from white to translucent yellow or brown.' This dried material is milled for a period of fifteen minutes.

Two hundred and fifty gms. of this milled product are suspended in 750 gms. of benzene and allowed to stand over night in a stoppered vessel, at room temperature. The following morning, a large proportion of the material will be foundto be dispersed. The residue on the bottom of the vessel may be dispersed by vigorous agitation. After standing for weeks, only a comparatively small amountof the incompletely dispersed material separates.

The viscose must not have "aged excessively at the time of use" Swollen fibrous particles will separate from the mixture 0E old viscose and latex. The length of time which viscose may be kept without excessive o5 deterioration depends upon the temperature at which it is kept, decomposition occurring more rapidly at hi her temperatures. We have found it possible, however, to use viscose which has been stored in a; glass vessel keptv in-an ice chest for as long as 15 to 20 days. The viscose-latex mixture should be kept at a temperature not exceeding 20 C.

We do not confine ourselves in this patent to the proportions referred to above, to the use of acetic acid as a coagulating medium,

to the method of drying, time of milling, or

to the use of benzene as a dispersing medium for the productobtained.

It will thus be seen that the present invention provides a simple'and practical fabble and impermeable to gases consisting in 10 ric for use on aircraft adapted to accomcoating the fabric with sizing and applying plish, among others, all of the objects and thereto a layer of a mixture of regenerated advantages herein set forth. cellulose and rubber redispersed in organic 6, What we claim as our invention is: solvents.

1. A fabric treated with a compound con- Signed at Washington, District of Columm sisting of a mixture of regenerated cellulose bia, this ninth day of January, 1925. and rubber redispersed in organic solvents. ISADORE M. JACOBSOHN.

2. A method of rendering a fabric flexi- STARR TRUSCOTT. 

